General Objective: To determine the carcinogenicity of radiotherapy and chemotherapy used in the treatment of Hodgkin's disease. Specific Aims: (1) To determine the variation in the risk of leukemia over 15 to 20 years after intensive chemotherapy for Hodgkin's disease. (2) To determine the risk of leukemia after treatment of Hodgkin's disease with specific drugs or categories of drugs. (3) To determine the risk of leukemia after intensive radiotherapy alone for Hodgkin's disease. (4) To determine the risk of leukemia after both intensive chemotherapy and intensive radiotherapy. (5) To determine the variation in the risk of solid cancers over 15 to 20 years after treatment for Hodgkin's disease. The risk of solid cancers will be determined for various treatments, including: intensive radiotherapy alone, intensive chemotherapy alone, intensive both, and radiotherapy to specific anatomic sites. Risks will be estimated for all solid cancers and for cancers of specific anatomic sites. (6) To determine the effect of patient characteristics such as age, and clinical characteristics such as the histopathologic type of Hodgkin's disease, on the risk of leukemia and solid cancers after various treatments for Hodgkin's disease. Methodology: A cohort of 10,000 subjects with Hodgkin's disease diagnosed between 1940 and 1984 will be identified. These 10,000 patients will be followed from their diagnosis of Hodgkin's disease in 1940-84 through 1990 or death before 1990, with follow-up information obtained as to survival, causes of death, and occurrence of second primary cancers. The association between treatment for Hodgkin's disease and subsequent risk of leukemia and solid cancer will be determined. Patients with Hodgkin's disease will be ascertained through registration records of large cancer therapy centers in the United States, Canada, and West Germany.